Sealing tubing

ABSTRACT

The invention concerns the sealing of tubing, and in particular the sealing of a joint between expandable tubing sections.  
     In one embodiment, there is disclosed expandable tubing such as an expandable liner ( 10 ) comprising at least two expandable tubing sections ( 18   a,   18   b ) which are adapted to be coupled together, and a seal ( 20 ) adapted to be located around the expandable tubing sections ( 18   a,   18   b ), to seal a joint ( 22 ) between the sections.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of Great Britain patent applicationserial number 0317547.8, filed Jul. 26, 2003, which is hereinincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the sealing of tubing. In particular,but not exclusively, the present invention relates to the sealing of ajoint between expandable tubing sections.

2. Description of the Related Art

In the oil and gas exploration and production industry, expandabletubing has been developed and has a variety of uses. These includeexpandable borehole casing and liner, and expandable sand exclusionbased tubing assemblies, such as those disclosed in International patentpublication no WO97/17524 (Shell), and as sold under the ESS Trademarkby the present applicant.

Expandable tubing offers a number of advantages over conventionalborehole tubing, as the expandable tubing can be run into a borehole inan unexpanded state and subsequently expanded downhole. This allows thetubing to be run through existing tubing and then expanded to a largerdiameter within the borehole.

The expandable tubing sections typically include a male threaded portion(pin) and a female threaded portion (box) at opposite ends, for joiningadjacent sections of tubing together end to end. Maintaining a sealbetween the pin and box portions post expansion can be problematic.

The sealing of sections of conventional, non-expandable tubing can alsobe problematic and can involve complex sealing systems.

It is amongst the objects of embodiments of the present invention toobviate or mitigate at least one of the foregoing disadvantages.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is providedexpandable tubing comprising:

-   -   at least two expandable tubing sections adapted to be coupled        together; and    -   a seal adapted to be located around the expandable tubing        sections, to seal a joint between the sections.

Preferably, the tubing sections are sections of downhole tubing. It willbe understood that the tubing sections are typically located in a borewithin a length of existing tubing such as borehole casing or liner, andthe seal is compressed between the casing/liner and the tubing sectionsduring tubing expansion, to ensure sealing at the section joints.Alternatively, the tubing sections may be located in open hole.

The expandable tubing sections may include connector portions atopposite ends of each section, for coupling the sections together end toend, to form a string of expandable tubing. The tubing may comprise aconnector having first and second portions, each portion adapted to beprovided on a respective expandable tubing section. The first and secondconnector portions may be formed integrally with the respective tubingsections, or may be formed separately and subsequently coupled to thetubing sections. The connector first and second portions may be threadedand may comprise respective threaded male and female portions, such asexpandable pin and box portions.

The seal may be adapted to be located overlapping a joint between thetubing sections. In this fashion, the seal acts to prevent fluid ingressand egress at the joint post expansion. Preferably, the seal isdeformable and most preferably resilient. The seal may therefore beelastically deformable. The seal may comprise at least one generallytubular member such as a sleeve, ring or collar, the tubular memberadapted to be coupled to the tubing sections to seal the joint.

The seal may be adapted to be located around the tubing sectionssubsequent to coupling of the tubing sections together and prior toexpansion of the tubing sections. Alternatively, the seal may be adaptedto be located around at least one of the tubing sections prior tocoupling of the tubing sections together.

The seal may comprise at least two seal members which may comprisesleeves, each tubing section having at least one seal member coupledthereto. The seal may include a first seal member adapted to be coupledto one tubing section and a second seal member adapted to be coupled toan adjacent tubing section, the first and second seal members adapted tobe brought into abutment to together form a seal, either when the tubingsections are coupled together or in a separate procedure followingcoupling of the tubing sections, for example, by translation of one orboth of the seal members along the tubing sections. To ensure adequatesealing post-expansion, the first and second seal members may be adaptedto be located overlapping respective axial end portions of the tubingsections, such that when the tubing sections are coupled together, endsof the seal members are pressed together and compressed. Thus whencoupled together, a mating force may be exerted on the seal members toseal the joint. It will be understood that when the tubing sections areexpanded and compressed between a wall of a borehole in which theexpandable tubing is located and the expandable tubing sections, theseal members are elongated, enhancing sealing at the interface betweenthe members.

Alternatively, the seal may be adapted to be mounted on one of thetubing sections and, following coupling, translated along the tubingsections to a location where the seal seals the joint, and may belocated straddling the joint.

In a further alternative, the seal may be adapted to be locatedextending beyond an end of one of the tubing sections prior to couplingthe sections together, and may be adapted to receive the other tubingsection, whereby on coupling the tubing sections, the joint is sealed.

Alternatively, the seal may be moveable from a first, non-sealingconfiguration to a second, sealing configuration following coupling ofthe tubing sections together, and may be adapted to be located on saidtubing section in a folded, non-sealing configuration. In analternative, the seal may be adapted to be located in a firstconfiguration extending beyond an end of one of the tubing sections andthen moved to a second, non-sealing configuration to expose said end,for coupling the tubing sections together. The seal may then be adaptedto be returned to the first configuration to seal the joint. The sealmay be deformable and is preferably elastically deformable.

In a further alternative embodiment, the seal members may be adapted tobe located spaced from one another and may be spaced axially along thetubing sections. The seal members may be adapted to be brought intoabutment during expansion of the tubing sections. Alternatively, theseal members may provide an adequate seal without being brought intoabutment, and may therefore remain axially spaced post expansion. Theseal may thus be established through an interaction between the tubingsections, the seal members and the wall of the borehole or tubular inwhich the tubing sections are located.

The seal may comprise an elastomeric material or a rubber material. Theseal may be adapted to swell in the presence of water and/orhydrocarbons and may comprise a swelling elastomer or a natural rubber.This provides enhanced seal performance over time as the seal absorbswater/hydrocarbons in the downhole environment and swells. The seal maybe coupled to the expandable tubing sections by an adhesive, or may bethermally bonded (for example, welded or fused) to the tubing sections.An outer surface of one or more tubing section may be textured orroughened to improve grip with the seal. Alternatively, the seal maycomprise a metal or metal alloy having a relatively low yield strengthand modulus of elasticity, such as bronze or lead. The seal maytherefore provide a metal to metal seal. In a further alternative, thetubing may include a recess, slot, groove, channel or the like in whichat least part of the seal is located.

The tubing may comprise a plurality of seals.

The seal may comprise at least two seal portions which may be ofmaterials having different material properties. For example, one of theseal portions may be of a material having a higher yield strength and/ormodulus of elasticity (Young's Modulus) than the other seal portion. Oneof the seal portions may be of a metal such as a steel or other alloy,and the other portion may be of an elastomeric or rubber material, or ametal or alloy having a relatively low yield strength and/or modulus.The seal may comprise an inner seal member and an outer seal memberadapted to be located around the inner seal member and the outer sealmember may comprise a sleeve, ring or collar and may extend over part orall of an unexpanded length of the inner seal member. In this fashion,when the tubing is expanded, the inner seal member is at least partlycompressed between the tubing sections and the outer seal member. Thisis of particular use where a surrounding borehole casing or liner hasdeteriorated such that an inner wall of the casing has become uneven,for example, through corrosion. In these circumstances, a seal withoutsuch an outer seal member may not be compressed sufficiently toadequately seal the section joint. The outer seal member, however,provides a consistent internal surface to compress the inner seal memberon expansion. This is of further use where the tubing is to be locatedin an open hole, where the borehole wall is typically uneven.

The outer seal member may carry the inner seal member and may include arecess such as a groove, slot, channel or the like in which the innerseal member is mounted. The outer seal member may carry a plurality ofinner seal members and may include a seal member adapted to be locatedeither side of the joint between the tubing sections.

Alternatively, the tubing may further comprise at least one restrainingor fixing member adapted to restrain the seal against axial movement inat least one axial direction. The restraining member may be coupled toor mounted on one of the tubing sections and may be adapted to receivethe seal. The restraining member may restrain the seal against axialmovement during expansion of the tubing, by translation of an expansiontool through the tubing. This may also protect the seal from damageand/or movement during run-in of the tubing into a borehole. Therestraining member and the seal may take the form of the outer and innerseal members, respectively, defined above.

In a further alternative, the tubing may further comprise at least onesupport or reinforcing member, the support member adapted to support theseal by providing a clamping force to securely clamp the seal pre and/orpost expansion to the tubing and/or to resist axial movement of theseal. The support member may be provided integrally with the seal memberand may, for example, be embedded or mounted in the seal. Alternatively,the support member may be provided externally of the seal, for example,mounted on or around a radially outer surface of the seal. The supportmember may comprise a sleeve, ring or the like; a plurality ofsleeves/rings; or a wire or cable. The seal and support member may takethe form of the inner and outer seal members, respectively, definedabove.

In a further alternative, the seal may comprise a plurality of sealmembers or portions of different material properties. For example, theseal may comprise at least one metal seal member, for metal to metalsealing, and at least one elastomeric or rubber seal member. The sealmembers may be adapted to cooperate with a corresponding seal membercarried by a tubing section.

The seal members may be spaced axially along the seal sleeve and/or thetubing such that when the seal is coupled to the tubing sections, aplurality of seals may be defined, adjacent seals optionally havingdifferent material properties.

According to a second aspect of the present invention, there is provideda string of expandable tubing comprising:

-   -   a plurality of expandable tubing sections coupled together; and    -   a plurality of seals located around a selected at least one of        the joints between the tubing sections.

Further features of the tubing sections and the seals are defined above.

According to a third aspect of the present invention, there is provideda connector for expandable tubing sections, the connector comprising:

-   -   first and second portions each adapted to be provided on a        respective expandable tubing section, the first and second        portions adapted to be coupled together; and    -   a seal adapted to be located around the first and second        portions to seal a joint between the portions.

It will be understood that the seal functions to seal the joint betweenthe first and second portions of the connector in the same fashion asthe joint between the expandable tubing sections, as described above.Further features of the connector and the seal are defined above.

According to a fourth aspect of the present invention, there is provideda seal for expandable tubing sections, the seal adapted to be locatedaround adjacent expandable tubing sections to seal a joint between thesections.

According to a fifth aspect of the present invention, there is provideda method of sealing a joint between expandable tubing sections, themethod comprising the steps of:

-   -   coupling expandable tubing sections together; and    -   locating a seal around the expandable tubing sections.

The method may comprise coupling the tubing sections together and thenlocating the seal around the tubing sections. The seal may be locatedoverlapping the joint between the tubing sections, and may straddle thejoint. In one embodiment, the seal may be mounted on one of the tubingsections and then translated to a location sealing the joint, where theseal may straddle the joint.

Alternatively, the method may comprise coupling a seal member to eachone of the tubing sections and subsequently coupling the tubing sectionstogether, to compress the seal members. The method may comprise locatingthe seal members overlapping axial end portions of the tubing sections.As described above, this may enhance sealing of the joint.

The method may comprise locating a seal comprising an inner seal memberaround the tubing sections and an outer seal member, of a materialhaving a higher yield strength and modulus of elasticity than the innerseal member, around the inner seal member. The outer seal member may belocated around the inner seal member subsequent to coupling the tubingsections together, or the inner and outer seal members may be providedas a seal unit to be located around the tubing sections together.

In a further alternative, the seal may be located with a portionextending beyond an end of one of the tubing sections prior to couplingthe sections together and the other tubing section may then be locatedin said portion and coupled to said tubing section.

In a still further alternative, the seal may be mounted on one of thetubing sections in a first configuration and then deformed or otherwisemoved to a second, non-sealing configuration, by deforming the seal(such as by folding the seal back). The tubing sections may then becoupled together and the seal subsequently returned to the firstconfiguration, to seal the tubing sections. Alternatively, the seal maybe mounted on said tubing section in a first, non-sealing configurationand subsequently moved to a second, sealing configuration.

The method may comprise restraining the seal against axial movement inat least one direction, for example, by coupling a restraining member toa tubing section and locating the seal in or coupling the seal to therestraining member.

The method may comprise clamping the seal to a tubing section using asupport or reinforcing member.

The step of locating the seal around the expandable tubing sections mayprovide at least an initial seal of the joint between the sections.Additionally or alternatively, the method may further comprise expandingthe tubing sections to compress the seal and seal the joint.

According to a fifth aspect of the present invention, there is provideda method of locating an expandable tubing in a borehole, the methodcomprising the steps of:

-   -   coupling a plurality of expandable tubing sections together;    -   locating a seal around a selected at least one joint between        adjacent tubing sections;    -   locating the expandable tubing in the borehole; and    -   expanding at least part of the expandable tubing, compressing        the at least one seal between the borehole and the expandable        tubing.

It will be understood that the tubing is typically located in tubingcasing, liner, expandable sand exclusion based tubing assemblies, orother tubing previously installed in the borehole or in an open holeenvironment.

According to a sixth aspect of the present invention, there is providedtubing comprising:

-   -   at least two tubing sections adapted to be coupled together; and    -   a seal adapted to be located around the tubing sections, to seal        a joint between the sections.

According to a seventh aspect of the present invention, there isprovided a method of sealing a joint between tubing sections, the methodcomprising the steps of:

-   -   coupling tubing sections together; and    -   locating a seal around the tubing sections.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal sectional view of expandable tubing inaccordance with an embodiment of the present invention, shown located ina casing lined borehole prior to expansion of the tubing;

FIG. 2 is a view of the tubing of FIG. 1 after expansion;

FIG. 3 is longitudinal sectional view of expandable tubing sectionsshown before being coupled together to form expandable tubing inaccordance with an alternative embodiment of the present invention;

FIG. 4 is a view of the expandable tubing sections of FIG. 3 coupledtogether to form the expandable tubing, shown located in a casing linedborehole but prior to expansion of the tubing;

FIG. 5 is a longitudinal sectional view of expandable tubing inaccordance with a further alternative embodiment of the presentinvention, shown located in a casing lined borehole prior to expansionof the tubing;

FIG. 6 is a longitudinal sectional view of expandable tubing inaccordance with a still further alternative embodiment of the presentinvention, shown located in a casing lined borehole prior to expansionof the tubing;

FIG. 7 is a longitudinal sectional view of expandable tubing inaccordance with a yet further alternative embodiment of the presentinvention, shown prior to coupling expandable tubing sections of thetubing together and prior to expansion of the tubing;

FIG. 8 is a view of the expandable tubing sections of FIG. 7 followingcoupling of the expandable tubing sections together;

FIG. 9 is a longitudinal sectional view of expandable tubing inaccordance with a yet further alternative embodiment of the presentinvention, shown prior to coupling expandable tubing sections of thetubing together and prior to expansion of the tubing;

FIGS. 10-12 are views illustrating steps in a method of coupling theexpandable tubing sections of FIG. 9 together;

FIG. 13 is a longitudinal half-sectional view of expandable tubing inaccordance with a yet further alternative embodiment of the presentinvention;

FIG. 14 is a longitudinal half-sectional view of expandable tubing inaccordance with a yet further alternative embodiment of the presentinvention;

FIG. 15 is a longitudinal half-sectional view of expandable tubing inaccordance with a yet further alternative embodiment of the presentinvention; and

FIG. 16 is a longitudinal half-sectional view of expandable tubing inaccordance with a yet further alternative embodiment of the presentinvention.

DETAILED DESCRIPTION OF DRAWINGS

Turning firstly to FIG. 1, there is shown a longitudinal sectional viewof expandable tubing in accordance with an embodiment of the presentinvention, the tubing indicated generally by reference numeral 10. Thetubing 10 is shown located in a borehole 12 which has previously beenlined with a casing 14, and cemented at 16, in a conventional fashion.The tubing 10 is shown in FIG. 1 prior to expansion of the tubing intocontact with the borehole casing 14.

In general terms, the expandable tubing 10 comprises expandable tubingsections 18 a, 18 b coupled together to form the tubing 10, and a seal20 located around the expandable tubing sections 18 a, 18 b, to seal ajoint 22 between the tubing sections.

The expandable tubing 10 which, in this embodiment, comprises a solidexpandable liner for gaining access to a hydrocarbon bearing formationbelow the casing 14, is first located in the borehole casing 14 as shownin FIG. 1. The liner tubing 10 is then expanded as shown in FIG. 2, tobring the seal 20 into contact with an inner wall 24 of the casing 14.The seal 20 is thus compressed between the inner wall 24 of the casing14 and an outer surface 26 of the tubing 10, to seal the joint 22. Thiscompression causes elongation of the seal 20.

In more detail, the expandable tubing 10 typically comprises a largenumber of expandable tubing sections coupled together to form anexpandable tubing string, which may extend for hundreds or thousands offeet along a length of the borehole 12. However, only two such sections18 a, 18 b are shown in the Figures.

Each tubing section 18 a, 18 b carries a male threaded portion 28,forming a pin, and a female threaded portion 30, forming a box, atopposite ends thereof. Adjacent sections of expandable tubing arecoupled together by threading the pin of one section into the box of anadjacent section, as shown in FIG. 1. The pin 28 of one section and thebox 30 of the adjacent section together form a connector 23. Both thepin 28 and box 30 are provided as short subs welded to the end ofrespective solid expandable tubes 32 a, 32 b, forming main parts of thetubing sections, and the pin 28 and box 30 are expandable.

The seal 20 comprises a short sleeve, of an elastomeric, rubber or metalof relatively low yield strength and modulus of elasticity, such asbronze or lead. The seal 20 is located around the joint 22 between thetubing sections 18 a, 18 b at surface following their coupling togetherand prior to running the expandable tubing 10 into the casing 14. Thisis achieved by first locating the seal 20 around the box 30 of thetubing section 18 b at a level below an end 34 of the box, and thenthreading the pin 28 of the tubing section 18a into the box 30, in aconventional fashion. The seal 20 is then moved upwardly to overlap thejoint 22, sealing the joint, and is fixed to the tubing sections usingan adhesive, or by welding or fusing. It will be understood that thisprocedure may be reversed and that the seal may be initially locatedaround the pin 28. Each joint between adjacent tubing sections formingthe expandable tubing 10 may be sealed in this fashion using seals 20,or only selected ones of the joints may be sealed.

The completed tubing 10 is then run into the casing 14, as shown in FIG.1, and is located relative to the casing 14 by any appropriate means.For example, the tubing 10 may be suspended from the casing 14 by aliner hanger. Alternatively, the tubing 10 is temporarily suspended fromsurface until such time as the tubing 10 has been expanded. An expansiontool, such as an expansion cone or mandrel, or a rotary tubing expansiontool such as that disclosed in the Applicant's International patentpublication no WO00/37766 (or a combination thereof), is then passedthrough the tubing 10, to radially expand the tubing. FIG. 2 illustratesthe tubing after expansion, where the tubing sections 18 a, 18 b havebeen radially expanded into contact with the casing inner wall 24. Theconnector 23 has also been expanded radially outwardly, compressing theseal 20 between the borehole inner wall 24 and the tubing outer surface26. It will be understood that the seal 20 is illustrated in anexaggerated fashion in FIG. 2, which may not represent the trueappearance of the seal following expansion of the tubing 10.

The seal 20 is thus held under compression to seal the joint 22,preventing fluid ingress from within or surrounding the casing 14 intothe tubing 10, or egress from the tubing 10 through the joint 22, as mayotherwise occur due to deformation of the pin 28 and box 30 during theexpansion process.

Turning now to FIG. 3, there is shown an expandable tubing in accordancewith an alternative embodiment of the present invention, the tubingindicated generally by reference numeral 100. Like components of thetubing 100 with the tubing 10 of FIGS. 1 and 2 share the same referencenumerals, incremented by 100. Only the main differences between thetubing 100 and the tubing 10 will be described in detail.

The tubing 100 comprises an expandable solid liner, and the seal 120comprises two seal portions in the form of first and second seal members36, 38, which are sleeves of a similar material to the seal 20 describedabove. However, the first sleeve 36 is carried by the pin 128 on tubingsection 118 a, whilst the second sleeve 38 is carried by the box 130 ontubing section 118 b. When the tubing sections 118 a, 118 b are coupledtogether as shown in FIG. 4, the first and second sleeves 36, 38 arebrought into abutment. The sleeves 36, 38 may be located overlapping endportions of the respective tubing sections. Specifically, the sleeve 36may be located overlapping a shoulder 40 on the pin 128, and the secondsleeve 38 overlapping the end 134 of the box 130. When the seal sleeves36, 38 are brought into abutment, there is an initial compression of thesleeves to provide a mating force which improves sealing of the joint122.

As shown in FIG. 4, the string of expandable tubing 100 is located in aborehole casing 114 in a similar fashion to the tubing 10, and is thenexpanded. Compression of the seal 120 results in an enhanced sealingeffect on the joint 122, as the seal sleeves 36, 38 elongate along thelength of the tubing 100 in the same way as the seal 22 illustrated inFIG. 2, enhancing the mating force between the sleeves.

Turning now to FIG. 5, there is shown a longitudinal sectional view ofan expandable tubing 200 in accordance with a further alternativeembodiment of the present invention, indicated generally by referencenumeral 200. The tubing 200 is similar to the tubing 10 of FIGS. 1 and2, and like components share the same reference numerals incremented by200.

The tubing 200 differs from the tubing 10 in that the seal 220 of thetubing 200 comprises two seal portions in the form of an inner sealmember 42 and an outer seal member 44. The inner seal member 42 is anelastomeric, rubber or metal seal sleeve, and the outer seal member 44is a seal sleeve 44 of a material having a higher yield strength and/ormodulus of elasticity than the inner seal sleeve 42, typically of ametal such as a steel. The outer seal sleeve 44 is located around theinner seal sleeve 42 following connection of the tubing sections 228 a,228 b together and location of the inner sleeve 42 around the joint 222.Alternatively, the seal 220 may be provided as a single unit.

When the tubing 200 is expanded, the inner seal sleeve 42 is compressedbetween the outer seal sleeve 44 and the outer surface 226 of the tubing200, to seal a joint 222 between sections 228 a, 228 b of the tubing.This ensures adequate sealing of the joint 222 in a deteriorated casing214, where the inner wall 224 of the casing 214 has suffered fromcorrosion and has become pitted. This typically results in the internalbore of the casing 214 being of an inconsistent internal diameter. Inthese circumstances, a seal of the type illustrated in FIG. 1 may not besufficient to ensure adequate sealing of the joint, as the seal 20 maynot be sufficiently compressed following expansion. This problem isobviated by use of the tubing 200.

FIG. 6 is a longitudinal sectional view of expandable tubing inaccordance with a further alternative embodiment of the presentinvention, the tubing indicated generally by reference numeral 300. Thetubing 300 comprises elastomeric inner seal sleeves 342 a, 342 b and ametal outer seal sleeve 344. The outer seal sleeve 344 is located aroundthe inner seal sleeves 342 a, 342 b following connection of tubingsections 328 a, 328 b together. The tubing 300 is expanded in a similarfashion to the tubing 200 of FIG. 5, and allows adequate sealing of ajoint 322 between the expandable tubing sections 328 a, 328 b, even in adeteriorated casing.

Turning now to FIG. 7, there is shown expandable tubing in accordancewith a yet further alternative embodiment of the present invention,indicated generally by reference numeral 400 and shown in FIG. 7 priorto connection of expandable tubing sections 418 a, 418 b together. Itwill be noted that like components of the tubing 400 with the tubing 10of FIGS. 1 and 2 share the same reference numerals, incremented by 400.

The tubing 400 includes a seal 420 located on a box 430 of the tubingsection 418 b with a portion 46 of the seal 420 overlapping andextending beyond an end 434 of the box 430. The pin 428 is mated withthe box 430 by locating the pin 428 in the portion 46 of the seal 420,before lowering the pin 428 and connecting the pin to the box 430. Theseal 420 is thus located prior to connection of the tubing sections 418a, 418 b, and seals the joint 422 between the tubing sections followingconnection.

Turning now to FIG. 9, there is shown a longitudinal sectional view ofexpandable tubing in accordance with a yet further alternativeembodiment of the present invention, the expandable tubing indicatedgenerally by reference numeral 500. Like components of the tubing 500with the tubing 10 of FIGS. 1 and 2 share the same reference numerals,incremented by 500.

In a similar fashion to the tubing 400 of FIGS. 7 and 8, the expandabletubing 500 includes a seal 520 which is located on a box 530 of a tubingsection 518 b prior to connecting with a pin 528 of an expandable tubingsection 518 a.

The seal 520 is located on the box 530 in a first configuration shown inFIG. 9. However, the seal 520 is elastically deformable and is folded orpeeled back away from an end 534 of the box to a second, non-sealingposition exposing the box end 534. The pin 528 is then lowered andconnected to the box 530, as shown in FIG. 11, and the seal 520 issubsequently returned to the first position, thereby sealing a joint 522between the expandable tubing sections 518 a, 518 b, as shown in FIG.12.

Turning now to FIG. 13, there is shown a longitudinal half-sectionalview of expandable tubing in accordance with a yet further alternativeembodiment of the present invention, the expandable tubing indicatedgenerally by reference numeral 600. Like components of the expandabletubing 600 with the expandable tubing 10 of FIGS. 1 and 2 share the samereference numerals, incremented by 600.

The expandable tubing 600 includes a seal 620 of an elastomeric or othermaterial, similar to the seal 20 of the expandable tubing 10. Arestraining member 638 in the form of a sleeve of a material having ahigher yield strength and/or Young's Modulus than the seal 620 ismounted on a box 630 of an expandable tubing section 618 b, and isshaped to receive the seal 620. The sleeve 638 restrains the seal 620against axial movement during expansion of the tubing 600, for example,by passing an expansion tool through the tubing 600 in the direction ofthe arrow A, and thus supports the seal 620.

Also, the sleeve 638 is tapered and thereby prevents damage to the seal620 when the tubing 600 is run into a borehole.

It will be understood that the principles behind construction of thetubing 600 may be applied to any one of the expandable tubings 10, 100,200, 300, 400 or 500 described above. In particular, the sleeve 638 mayextend along a majority of a length of the seal 620, affording theadvantages described above in relation to the expandable tubing 200 or300.

Turning now to FIG. 14, there is shown a longitudinal half-section viewof expandable tubing in accordance with a yet further alternativeembodiment of the present invention, the expandable tubing indicatedgenerally by reference numeral 700. Like components of the tubing 700with the tubing 10 of FIGS. 1 and 2 share the same reference numeralsincremented by 700.

The tubing 700 includes a seal 720, typically of an elastomeric materialand a support or reinforcing member 738 in the form of a sleeve of ahigher yield strength and/or Young's Modulus than the seal 720.

The sleeve 738 is formed integrally with the elastomeric seal 736, butmay equally be mounted on an outer surface or otherwise coupled to theseal 736. The sleeve 738 exerts a clamping force on the seal 720, toassist in maintaining the seal 720 in a position sealing a joint 722between expandable tubing sections 718 a, 718 b of the tubing 700 bothduring run-in to a borehole and following expansion.

Turning now to FIG. 15, there is shown a longitudinal half-sectionalview of expandable tubing in accordance with a yet further alternativeembodiment of the present invention, the expandable tubing indicatedgenerally by reference numeral 800. Like components of the expandabletubing 800 with the expandable tubing 10 of FIGS. 1 and 2 share the samereference numerals, incremented by 800.

The expandable tubing 800 is essentially similar to the expandabletubing 700 of FIG. 14, except the tubing 800 includes a seal 820 and asupport or reinforcing member in the form of a number of wires or cables838 formed integrally with, or mounted on or around the seal 820, toprovide a clamping force.

Where the wires 838 (or indeed the sleeve 738 of tubing 700) is locatedaround the seal 820, or for example in a groove in the seal, the tubingsections 818 a, 818 b may be coupled together and sealed using one ofthe structures and according to one of the methods described above. Thewires may then subsequently be located around the seal 820, to provide aclamping force. This facilitates mounting of the seal 820 on the tubingby only creating the clamping force after coupling and sealing of thetubing sections 818 a, 818 b.

Turning now to FIG. 16, there is shown a longitudinal half-sectionalview of expandable tubing in accordance with a yet further alternativeembodiment of the present invention, the expandable tubing indicatedgenerally by reference numeral 900. Like components of the expandabletubing 900 with the expandable tubing 10 of FIGS. 1 and 2 share the samereference numerals, incremented by 900.

The expandable tubing 900 essentially combines the features of theexpandable tubing 600, 700 and 800 of FIGS. 13, 14 and 15. Thus thetubing 900 includes a seal 920 with a restraining sleeve 938 a, a sleeve938 b which exerts a clamping force on the seal 920, and reinforcingwires 938c, thereby combining each of the advantages discussed above.

In particular, the sleeve 938 b may exert a relatively greater clampingforce than the wires 938 c, facilitating connection of the expandabletubing sections 918 a, 918 b. For example, the sleeve 938 b may beprovided integrally with the seal 920, and the wires 938 c mountedaround the seal 920 following connection of the tubing sections 918 a,918 b. This facilitates connection of the tubing sections 918 a, 918 bin that the clamping force exerted by the wires 938 c is only exertedsubsequent to coupling of the tubing sections.

It will be understood that, in further alternative embodiments, a sealmay be provided incorporating two sleeves, which may take the form ofthe sleeve 738 of tubing 700, the sleeves spaced either side of thejoint 722, or indeed wires such as the wires 838 of tubing 800 may beprovided on both sides of the joint 822. In a further alternative, theconfiguration of the sleeve 938 b and wires 938 c in the tubing 900 ofFIG. 16 may be reversed, such that the wires 938 c are provided aroundthe portion of the seal 920 on the box 930. Also, the sleeve/wire mayoverlap the respective joint.

Furthermore, any one of the seals may be angled (tapered) in the fashionof the seals 620, 920 of the tubing 600 or 900.

It will be understood that the principles of any of the tubings 700, 800or 900 may equally be employed with the tubings 10, 100, 200, 300, 400or 500 described above.

Various modifications may be made to the foregoing with the scope of thepresent invention.

For example, the tubing may comprise slotted or otherwise perforatedtubing, and may comprise an expandable sand exclusion tubing basedassembly, such as the Applicant's ESS (Trademark). The tubing may beused in an open hole environment. The tubing sections may be coupledtogether in any suitable fashion, such as by stab, snap fit or latchlock connections. The seal and the inner seal members may swell in thepresence of water and/or hydrocarbons, such as borehole fluids (oils andgasses) and may comprise a swelling elastomer.

The outer seal member may carry the inner seal member and may include arecess such as a groove, slot, channel or the like in which the innerseal member is mounted. The outer seal member may carry a plurality ofinner seal members and may be adapted to provide a seal member spacedeither side of the joint between the tubing sections.

In a further alternative, the seal may comprise a plurality of sealmembers or portions of different material properties. For example, theseal may comprise at least one metal seal member, for metal to metalsealing, and at least one elastomeric or rubber seal member. The sealmembers may be adapted to cooperate with a corresponding seal membercarried by a tubing section. The seal member may comprise an outer sealsleeve including at least one seal member extending inwardly of the sealsleeve and with at least one separate seal member of a differentmaterial mounted on the seal sleeve or a tubing section. The sealmembers may be of an elastomeric, rubber or metal of lower strengthand/or modulus of elasticity. The seal members may be spaced axiallyalong the seal sleeve and/or the tubing such that when the seal iscoupled to the tubing sections, a plurality of seals may be defined,adjacent seals optionally having different material properties.

Furthermore, whilst the present invention is described herein inrelation to expandable tubing, it will be understood that the principlesof the invention may equally be employed with non-expandable tubing,such as non-expandable downhole tubing (for example, conventionalcasing, liner or the like), or indeed with other types of tubing notfound in the downhole environment, such as pipeline.

1. Expandable tubing comprising: at least two expandable tubing sectionsadapted to be coupled together; and a seal adapted to be located aroundthe expandable tubing sections, to seal a joint between the sections. 2.Expandable tubing as claimed in claim 1, comprising a connector havingfirst and second portions, each portion adapted to be provided on arespective expandable tubing section.
 3. Expandable tubing as claimed inclaim 2, wherein the first and second connector portions are formedintegrally with the respective tubing sections.
 4. Expandable tubing asclaimed in claim 2, wherein the first and second connector portions areformed separately and subsequently coupled to the tubing sections. 5.Expandable tubing as claimed in claim 2, wherein the connector first andsecond portions comprise respective threaded male and female portions.6. Expandable tubing as claimed in claim 1, wherein the seal is adaptedto be located overlapping the joint between the tubing sections. 7.Expandable tubing as claimed in claim 1, wherein the seal is deformable.8. Expandable tubing as claimed in claim 7, wherein the seal isresilient.
 9. Expandable tubing as claimed in claim 1, wherein the sealis adapted to be located around the tubing sections subsequent tocoupling of the tubing sections together.
 10. Expandable tubing asclaimed in claim 1, wherein the seal is adapted to be located around thetubing sections prior to coupling of the tubing sections together. 11.Expandable tubing as claimed in claim 1, wherein the seal comprises atleast two seal members, each tubing section having at least one sealmember coupled thereto.
 12. Expandable tubing as claimed in claim 11,wherein the seal includes a first seal member adapted to be coupled toone tubing section and a second seal member adapted to be coupled to anadjacent tubing section, the first and second seal members adapted to bebrought into abutment.
 13. Expandable tubing as claimed in claim 12,wherein the first and second seal members are adapted to be locatedoverlapping respective axial end portions of the tubing sections, suchthat when the tubing sections are coupled together, ends of the sealmembers are adapted to be compressed.
 14. Expandable tubing as claimedin claim 12, wherein the first and second seal members are adapted to bebrought into abutment when the tubing sections are coupled together. 15.Expandable tubing as claimed in claim 12, wherein the first and secondseal members are adapted to be brought into abutment in a separateprocedure following coupling of the tubing sections.
 16. Expandabletubing as claimed in claim 15, wherein the seal members are adapted tobe translated along the tubing sections.
 17. Expandable tubing asclaimed in claim 11, wherein the seal includes a first seal memberadapted to be coupled to one tubing section and a second seal memberadapted to be coupled to an adjacent tubing section, and wherein theseal members are adapted to be located spaced from one another. 18.Expandable tubing as claimed in claim 17, wherein the seal members areadapted to be brought into abutment during expansion of the tubing. 19.Expandable tubing as claimed in claim 17, wherein the seal membersremain spaced post expansion.
 20. Expandable tubing as claimed in claim1, wherein the seal is adapted to be mounted on one of the tubingsections and translated along the tubing sections to a location wherethe seal seals the joint, following coupling of the tubing sections. 21.Expandable tubing as claimed in claim 20, wherein the seal is adapted tobe located straddling the joint.
 22. Expandable tubing as claimed inclaim 1, wherein the seal is adapted to be located extending beyond anend of one of the tubing sections prior to coupling the sectionstogether, and to receive the other tubing section, whereby on couplingthe tubing sections, the joint is sealed.
 23. Expandable tubing asclaimed in claim 1, wherein the seal is moveable from a first,non-sealing configuration to a second, sealing configuration followingcoupling of the tubing sections together.
 24. Expandable tubing asclaimed in claim 23, wherein the seal is adapted to be located on saidtubing section in a folded, non-sealing configuration.
 25. Expandabletubing as claimed in claim 1, wherein the seal is adapted to be locatedin a first configuration extending beyond an end of one of the tubingsections and then moved to a second, non-sealing configuration to exposesaid end, for coupling the tubing sections together, and to besubsequently returned to the first configuration to seal the joint. 26.Expandable tubing as claimed in claim 1, wherein the seal comprises anelastomeric material.
 27. Expandable tubing as claimed in claim 1,wherein the seal comprises a rubber material.
 28. Expandable tubing asclaimed in claim 1, wherein the seal is adapted to swell in the presenceof at least one of water and hydrocarbons.
 29. Expandable tubing asclaimed in claim 1, wherein the seal comprises a metal having a lowyield strength and modulus of elasticity relative to the tubingsections.
 30. Expandable tubing as claimed in claim 1, wherein thetubing includes a recess in which at least part of the seal is located.31. Expandable tubing as claimed in claim 1, comprising a plurality ofseals.
 32. Expandable tubing as claimed in claim 1, comprising at leasttwo seal portions of materials having different material properties. 33.Expandable tubing as claimed in claim 32, wherein the seal portions areof materials having different yield strength and modulus of elasticity.34. Expandable tubing as claimed in claim 32, comprising an inner sealmember, and an outer seal member adapted to be located around the innerseal member.
 35. Expandable tubing as claimed in claim 34, wherein theouter seal member is of a material having a higher yield strength andmodulus of elasticity than the inner seal member.
 36. Expandable tubingas claimed in claim 34, wherein the outer seal member extends over atleast part of an unexpanded length of the inner seal member. 37.Expandable tubing as claimed in claim 34, wherein the outer seal memberincludes a recess in which the inner seal member is mounted. 38.Expandable tubing as claimed in claim 37, wherein a plurality of innerseal members are coupled to the outer seal member, and wherein a sealmember is adapted to be located either side of the joint between thetubing sections.
 39. Expandable tubing as claimed in claim 1, furthercomprising at least one restraining member adapted to restrain the sealagainst axial movement in at least one axial direction.
 40. Expandabletubing as claimed in claim 39, wherein the restraining member is coupledto one of the tubing sections and adapted to receive the seal. 41.Expandable tubing as claimed in claim 39, wherein the seal and therestraining member take the form of an inner seal member, and an outerseal member adapted to be located around the inner seal member. 42.Expandable tubing as claimed in claim 1, further comprising at least onesupport member adapted to support the seal by providing a clamping forceto securely clamp the seal to the tubing.
 43. Expandable tubing asclaimed in claim 42, wherein a support member is provided integrallywith the seal.
 44. Expandable tubing as claimed in claim 43, wherein asupport member is mounted in the seal.
 45. Expandable tubing as claimedin claim 42, wherein a support member is provided externally of theseal.
 46. Expandable tubing as claimed in claim 45, wherein a supportmember is mounted on a radially outer surface of the seal. 47.Expandable tubing as claimed in claim 42, wherein the support membercomprises a sleeve.
 48. Expandable tubing as claimed in claim 42,wherein the support member comprises a wire.
 49. Expandable tubing asclaimed in claim 42, wherein the seal and the support member take theform of an inner seal member, and an outer seal member adapted to belocated around the inner seal member.
 50. Expandable tubing as claimedin claim 1, wherein the seal comprises a plurality of seal members ofdifferent material properties.
 51. Expandable tubing as claimed in claim50, wherein the seal members are adapted to cooperate with correspondingseal members on the tubing sections.
 52. Expandable tubing as claimed inclaim 1, wherein the seal comprises a plurality of seal members spacedaxially along the tubing.
 53. Expandable tubing as claimed in claim 52,wherein adjacent seals have different material properties.
 54. A stringof expandable tubing comprising: a plurality of expandable tubingsections coupled together; and a plurality of seals located around aselected at least one of the joints between the tubing sections.
 55. Aconnector for expandable tubing sections, the connector comprising:first and second portions each adapted to be provided on a respectiveexpandable tubing section, the first and second portions adapted to becoupled together; and a seal adapted to be located around the first andsecond portions to seal a joint between the portions.
 56. A seal forexpandable tubing sections, the seal adapted to be located aroundadjacent expandable tubing sections to seal a joint between thesections.
 57. A method of sealing a joint between expandable tubingsections, the method comprising the steps of: coupling expandable tubingsections together; and locating a seal around the expandable tubingsections.
 58. A method as claimed in claim 57, comprising coupling thetubing sections together and then locating the seal around the tubingsections.
 59. A method as claimed in claim 57, comprising locating theseal overlapping the joint between the tubing sections.
 60. A method asclaimed in claim 57, comprising mounting the seal on one of the tubingsections and translating the seal to a location sealing the joint.
 61. Amethod as claimed in claim 60, comprising translating the seal to alocation straddling the joint.
 62. A method as claimed in claim 57,comprising coupling a seal member to each one of the tubing sections andsubsequently coupling the tubing sections together, to compress the sealmembers.
 63. A method as claimed in claim 62, comprising locating theseal members overlapping axial end portions of the respective tubingsections.
 64. A method as claimed in claim 57, comprising locating aseal comprising an inner seal member around the tubing sections and anouter seal member, of a material having a higher yield strength andmodulus of elasticity than the inner seal member, around the inner sealmember.
 65. A method as claimed in claim 64, comprising locating theouter seal member around the inner seal member subsequent to couplingthe tubing sections together.
 66. A method as claimed in claim 64,comprising providing the inner and outer seal members as a seal unit andlocating the unit around the tubing sections.
 67. A method as claimed inclaim 57, comprising locating the seal with a portion extending beyondan end of one of the tubing sections prior to coupling the sectionstogether, and then locating the other tubing section in said portion andcoupling the tubing sections together.
 68. A method as claimed in claim57, comprising mounting the seal on one of the tubing sections in afirst configuration and then moving the seal to a second, non-sealingconfiguration.
 69. A method as claimed in claim 68, further comprisingsubsequently coupling the tubing sections together and returning theseal to the first configuration, to seal the tubing sections.
 70. Amethod as claimed in claim 57, comprising mounting the seal on one ofthe tubing sections in a first, non-sealing configuration, coupling thetubing sections together and then moving the seal to a second, sealingconfiguration.
 71. A method as claimed in claim 57, further comprisingrestraining the seal against axial movement in at least one direction.72. A method as claimed in claim 57, further comprising clamping theseal to a tubing section.
 73. A method as claimed in claim 57, whereinthe step of locating the seal around the expandable tubing sectionsprovides at least an initial seal of a joint between the sections.
 74. Amethod as claimed in claim 57, further comprising expanding the tubingsections to compress the seal and seal the joint.
 75. A method oflocating an expandable tubing in a borehole, the method comprising thesteps of: coupling a plurality of expandable tubing sections together;locating a seal around a selected at least one joint between adjacenttubing sections; locating the expandable tubing in the borehole; andexpanding at least part of the expandable tubing, compressing the atleast one seal between the borehole and the expandable tubing.